1 files changed, 359 insertions, 0 deletions

diff --git a/security/keys/request_key.c b/security/keys/request_key.c
new file mode 100644
index 000000000000..9705b1aeba5d
--- /dev/null
+++ b/security/keys/request_key.c
@@ -0,0 +1,359 @@
+/* request_key.c: request a key from userspace
+ *
+ * Copyright (C) 2004 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/module.h>
+#include <linux/sched.h>
+#include <linux/kmod.h>
+#include <linux/err.h>
+#include "internal.h"
+
+struct key_construction {
+        struct list_head        link;   /* link in construction queue */
+        struct key              *key;   /* key being constructed */
+};
+
+/* when waiting for someone else's keys, you get added to this */
+DECLARE_WAIT_QUEUE_HEAD(request_key_conswq);
+
+/*****************************************************************************/
+/*
+ * request userspace finish the construction of a key
+ * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring> <info>"
+ * - if callout_info is an empty string, it'll be rendered as a "-" instead
+ */
+static int call_request_key(struct key *key,
+                            const char *op,
+                            const char *callout_info)
+{
+        struct task_struct *tsk = current;
+        unsigned long flags;
+        key_serial_t prkey, sskey;
+        char *argv[10], *envp[3], uid_str[12], gid_str[12];
+        char key_str[12], keyring_str[3][12];
+        int i;
+
+        /* record the UID and GID */
+        sprintf(uid_str, "%d", current->fsuid);
+        sprintf(gid_str, "%d", current->fsgid);
+
+        /* we say which key is under construction */
+        sprintf(key_str, "%d", key->serial);
+
+        /* we specify the process's default keyrings */
+        sprintf(keyring_str[0], "%d",
+                tsk->thread_keyring ? tsk->thread_keyring->serial : 0);
+
+        prkey = 0;
+        if (tsk->signal->process_keyring)
+                prkey = tsk->signal->process_keyring->serial;
+
+        sskey = 0;
+        spin_lock_irqsave(&tsk->sighand->siglock, flags);
+        if (tsk->signal->session_keyring)
+                sskey = tsk->signal->session_keyring->serial;
+        spin_unlock_irqrestore(&tsk->sighand->siglock, flags);
+
+
+        if (!sskey)
+                sskey = tsk->user->session_keyring->serial;
+
+        sprintf(keyring_str[1], "%d", prkey);
+        sprintf(keyring_str[2], "%d", sskey);
+
+        /* set up a minimal environment */
+        i = 0;
+        envp[i++] = "HOME=/";
+        envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
+        envp[i] = NULL;
+
+        /* set up the argument list */
+        i = 0;
+        argv[i++] = "/sbin/request-key";
+        argv[i++] = (char *) op;
+        argv[i++] = key_str;
+        argv[i++] = uid_str;
+        argv[i++] = gid_str;
+        argv[i++] = keyring_str[0];
+        argv[i++] = keyring_str[1];
+        argv[i++] = keyring_str[2];
+        argv[i++] = callout_info[0] ? (char *) callout_info : "-";
+        argv[i] = NULL;
+
+        /* do it */
+        return call_usermodehelper(argv[0], argv, envp, 1);
+
+} /* end call_request_key() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace for the key
+ * - called with the construction sem held, but the sem is dropped here
+ * - we ignore program failure and go on key status instead
+ */
+static struct key *__request_key_construction(struct key_type *type,
+                                              const char *description,
+                                              const char *callout_info)
+{
+        struct key_construction cons;
+        struct timespec now;
+        struct key *key;
+        int ret, negative;
+
+        /* create a key and add it to the queue */
+        key = key_alloc(type, description,
+                        current->fsuid, current->fsgid, KEY_USR_ALL, 0);
+        if (IS_ERR(key))
+                goto alloc_failed;
+
+        write_lock(&key->lock);
+        key->flags |= KEY_FLAG_USER_CONSTRUCT;
+        write_unlock(&key->lock);
+
+        cons.key = key;
+        list_add_tail(&cons.link, &key->user->consq);
+
+        /* we drop the construction sem here on behalf of the caller */
+        up_write(&key_construction_sem);
+
+        /* make the call */
+        ret = call_request_key(key, "create", callout_info);
+        if (ret < 0)
+                goto request_failed;
+
+        /* if the key wasn't instantiated, then we want to give an error */
+        ret = -ENOKEY;
+        if (!(key->flags & KEY_FLAG_INSTANTIATED))
+                goto request_failed;
+
+        down_write(&key_construction_sem);
+        list_del(&cons.link);
+        up_write(&key_construction_sem);
+
+        /* also give an error if the key was negatively instantiated */
+ check_not_negative:
+        if (key->flags & KEY_FLAG_NEGATIVE) {
+                key_put(key);
+                key = ERR_PTR(-ENOKEY);
+        }
+
+ out:
+        return key;
+
+ request_failed:
+        /* it wasn't instantiated
+         * - remove from construction queue
+         * - mark the key as dead
+         */
+        negative = 0;
+        down_write(&key_construction_sem);
+
+        list_del(&cons.link);
+
+        write_lock(&key->lock);
+        key->flags &= ~KEY_FLAG_USER_CONSTRUCT;
+
+        /* check it didn't get instantiated between the check and the down */
+        if (!(key->flags & KEY_FLAG_INSTANTIATED)) {
+                key->flags |= KEY_FLAG_INSTANTIATED | KEY_FLAG_NEGATIVE;
+                negative = 1;
+        }
+
+        write_unlock(&key->lock);
+        up_write(&key_construction_sem);
+
+        if (!negative)
+                goto check_not_negative; /* surprisingly, the key got
+                                          * instantiated */
+
+        /* set the timeout and store in the session keyring if we can */
+        now = current_kernel_time();
+        key->expiry = now.tv_sec + key_negative_timeout;
+
+        if (current->signal->session_keyring) {
+                unsigned long flags;
+                struct key *keyring;
+
+                spin_lock_irqsave(&current->sighand->siglock, flags);
+                keyring = current->signal->session_keyring;
+                atomic_inc(&keyring->usage);
+                spin_unlock_irqrestore(&current->sighand->siglock, flags);
+
+                key_link(keyring, key);
+                key_put(keyring);
+        }
+
+        key_put(key);
+
+        /* notify anyone who was waiting */
+        wake_up_all(&request_key_conswq);
+
+        key = ERR_PTR(ret);
+        goto out;
+
+ alloc_failed:
+        up_write(&key_construction_sem);
+        goto out;
+
+} /* end __request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * call out to userspace to request the key
+ * - we check the construction queue first to see if an appropriate key is
+ *   already being constructed by userspace
+ */
+static struct key *request_key_construction(struct key_type *type,
+                                            const char *description,
+                                            struct key_user *user,
+                                            const char *callout_info)
+{
+        struct key_construction *pcons;
+        struct key *key, *ckey;
+
+        DECLARE_WAITQUEUE(myself, current);
+
+        /* see if there's such a key under construction already */
+        down_write(&key_construction_sem);
+
+        list_for_each_entry(pcons, &user->consq, link) {
+                ckey = pcons->key;
+
+                if (ckey->type != type)
+                        continue;
+
+                if (type->match(ckey, description))
+                        goto found_key_under_construction;
+        }
+
+        /* see about getting userspace to construct the key */
+        key = __request_key_construction(type, description, callout_info);
+ error:
+        return key;
+
+        /* someone else has the same key under construction
+         * - we want to keep an eye on their key
+         */
+ found_key_under_construction:
+        atomic_inc(&ckey->usage);
+        up_write(&key_construction_sem);
+
+        /* wait for the key to be completed one way or another */
+        add_wait_queue(&request_key_conswq, &myself);
+
+        for (;;) {
+                set_current_state(TASK_UNINTERRUPTIBLE);
+                if (!(ckey->flags & KEY_FLAG_USER_CONSTRUCT))
+                        break;
+                schedule();
+        }
+
+        set_current_state(TASK_RUNNING);
+        remove_wait_queue(&request_key_conswq, &myself);
+
+        /* we'll need to search this process's keyrings to see if the key is
+         * now there since we can't automatically assume it's also available
+         * there */
+        key_put(ckey);
+        ckey = NULL;
+
+        key = NULL; /* request a retry */
+        goto error;
+
+} /* end request_key_construction() */
+
+/*****************************************************************************/
+/*
+ * request a key
+ * - search the process's keyrings
+ * - check the list of keys being created or updated
+ * - call out to userspace for a key if requested (supplementary info can be
+ *   passed)
+ */
+struct key *request_key(struct key_type *type,
+                        const char *description,
+                        const char *callout_info)
+{
+        struct key_user *user;
+        struct key *key;
+
+        /* search all the process keyrings for a key */
+        key = search_process_keyrings_aux(type, description, type->match);
+
+        if (PTR_ERR(key) == -EAGAIN) {
+                /* the search failed, but the keyrings were searchable, so we
+                 * should consult userspace if we can */
+                key = ERR_PTR(-ENOKEY);
+                if (!callout_info)
+                        goto error;
+
+                /* - get hold of the user's construction queue */
+                user = key_user_lookup(current->fsuid);
+                if (!user) {
+                        key = ERR_PTR(-ENOMEM);
+                        goto error;
+                }
+
+                for (;;) {
+                        /* ask userspace (returns NULL if it waited on a key
+                         * being constructed) */
+                        key = request_key_construction(type, description,
+                                                       user, callout_info);
+                        if (key)
+                                break;
+
+                        /* someone else made the key we want, so we need to
+                         * search again as it might now be available to us */
+                        key = search_process_keyrings_aux(type, description,
+                                                          type->match);
+                        if (PTR_ERR(key) != -EAGAIN)
+                                break;
+                }
+
+                key_user_put(user);
+        }
+
+ error:
+        return key;
+
+} /* end request_key() */
+
+EXPORT_SYMBOL(request_key);
+
+/*****************************************************************************/
+/*
+ * validate a key
+ */
+int key_validate(struct key *key)
+{
+        struct timespec now;
+        int ret = 0;
+
+        if (key) {
+                /* check it's still accessible */
+                ret = -EKEYREVOKED;
+                if (key->flags & (KEY_FLAG_REVOKED | KEY_FLAG_DEAD))
+                        goto error;
+
+                /* check it hasn't expired */
+                ret = 0;
+                if (key->expiry) {
+                        now = current_kernel_time();
+                        if (now.tv_sec >= key->expiry)
+                                ret = -EKEYEXPIRED;
+                }
+        }
+
+ error:
+        return ret;
+
+} /* end key_validate() */
+
+EXPORT_SYMBOL(key_validate);